Migration of an operating system (OS) from a physical machine to a virtual environment is performed by copying a disk image (information stored in a secondary storage unit such as a hard disk drive (HDD)) of the OS from the physical machine to a virtual machine. This technology makes it possible to migrate an OS running directly on a physical machine to a virtual machine running on another physical machine.
However, with a method of copying a disk image of an OS from a physical machine to a virtual machine, it is necessary to start the OS on the virtual machine based on the copied disk image. In other words, it is necessary to restart the OS during the migration. Restarting an OS indicates the loss of continuity of a process (or service) being executed on the OS.
Here, Japanese Laid-Open Patent Publication No. 2009-145931 discloses a technology that intends to reduce the period of interruption of a service which occurs when an OS is migrated from a physical machine to a virtual machine.
JP2009-145931, however, does not provide measures for preventing problems resulting from differences (or inconsistency) between devices (e.g., network cards and HDDs) available in a physical machine and a virtual machine. Generally, the same devices available in the physical machine are not always available in the virtual machine. If devices in the physical machine are different from devices in the virtual machine, it is highly likely that a process being executed using the devices in the physical machine before migration cannot be continued after the migration. That is, it is highly likely that processes for controlling the devices cannot be correctly performed after the migration.